Note: After you have worked on the problems below, you can look at Selected Answers.

• Material you are responsible for:
  • Week 8 Lectures Data Types and Assignments
  • Week 9 Lectures Data Types and Assignments
  • Week 10 Lectures Decisions
  • Week 11 Lectures Decisions (The last third of the Week 11 Lectures, after "precedence of operators", will not be covered at all.

  • Lab 7 Assignments: the Pair class
  • Lab 8 Assignments: the TimeInterval class
  • Lab 9 Conditionals: the Paycheck class
  • Lab 10 Conditionals: the CombinationLock class

  • Extra Materials

• How to study: Do not just read the material over, but instead start up JBuilder and try out many of the pieces of code inside actual Java programs.

• Topics:
  • Operators and precedence:

    In Week 8, we had arithmetic operators: + / % + -
    In Week 10, we added comparison operators: == > < != >= <=
    In Week 11, we added logical operators: ! && ||
    assignement operator: =
    increment and decrement operators: ++ --
    Week 11 give a large precedence table (do not memorize)

  • Primitive types:

    double, int, and boolean
    Use the operators above on these

  • Objects (all other types):

    Example: String type
    Must not use comparison operators on Strings.
    Use the method equals instead of == !=
    Use the method compareTo as a replacement for all comparison operators
    Also use + to concatenate (tack together) Strings.

  • if-else statements:

    See Week 10 and Week 11 lectures for many examples.

• How do you translate a mathematical equation, such as the quadratic formula, into Java?

• Given and integer, such as int n = 47;, how do you use the / and % operators to pick off the ten's digit and the unit's digit?

• Starting with two integers, say int a = 47; and int b = 89;, how can you use an extra integer location, say int temp; and three assignments to interchange the values in a and b?

• As in the previous example, also use an if statement to ensure that, no matter what the starting values of a and b, after the statement the two values are the same, but possibly interchanged so that a <= b is always true.

• Give several different ways to increase the value of an integer variable, say int x; by one.

• Start with two strings, say s1 and s2. Use an if-else statement and the equals method to check if the strings are equal, and to print either EQUAL or print NOT EQUAL. (You must not use either of the operators == or !=.)

• Start with two strings, say s1 and s2. Use an extended if-else statement and the compareTo method to do a dictionary order comparison of the two strings. Your statement should print one of the three messages: FIRST-BEFORE-SECOND, FIRST-AFTER-SECOND, or FIRST-EQUALS-SECOND.

• Work out the examples in the Activity 1 of the Week 10 lecture:
  • Assign theMin to be the smaller of x and y
  • Write an if statement that assigns 100 to x when y is equal to 0.
  • Write an if-else statement that assigns 0 to x when y is equal to 10.  Otherwise it should assign 1 to x.
  • Write an if statement that sets the variable hours to 10 when the boolean variable minumum is equal to true
  • Calculate wages as hoursWorked times hourlyRate with time and a half for overtime (hours over 40)

• Work out the first three examples in the Activity 2 of the Week 11 lecture:
  • Write an if statement that prints the message "The number is valid" if the variable grade is within the range 0 through 100 inclusive.
  • Write an if statement that prints the message "The number is valid" if the variable temperture is within the range -50 through 150 inclusive.
  • Write an if statement that prints the message "The number is not valid" if the variable hours is outside the range 0 through 80 inclusive.

• Given a table such as the one given in the The Commission class, write an if-else statement to set the value correctly. (Three answers given.)

• Given and integer number of points on and exam in the variable int points;, print the proper grade using the table below:

  points	Grade
  greater than 100	A+
  90 to 100 inclusive	A
  80 to 89 inclusive	B
  70 to 79 inclusive	C
  60 to 79 inclusive	D
  0 to 59 inclusive	F
  less than 0	Invalid

• I plan to have a question involving a class and a test class (with a main function). I will supply a description and part of the code. You will have to fill in various missing parts. For example, I may ask you to supply constructor(s) or method(s) in the class, and to use these in the main function. At least somewhere you will need to use assignments, arithmetic operators, comparison operators, and if-else statements.

  You have prepared for this question by having done the labs. The question will be similar to these labs, but simpler. You can also prepare by looking over or working out the two extra review classes in the Week 12 Review: the Triangle class, and the RomanNumeral class. (Note that the switch statement in the answer to the question about the RomanNumeral class in not required. It can easily be done with an extended if-else statement.)